JPH08256493A - Motor driver - Google Patents

Abstract

PURPOSE: To realize a current zero condition simply and surely, and surely stop the revolution of a motor in case that the motor control becomes abnormal, without using mechanical means. CONSTITUTION: AND gates 8 and 9 are provided between an FET 2, which turns on or turns off the application of voltage on high level side to a coil, and a comparator 6 which turns on and turns off this FET 2, based on the control signal. An AND gate 12 and an OR gate 13 are provided between an FET 3, which turns on or turns off the application of voltage to a low level side to the coil 1, and an inverter 11 which turns or turns off this FET 13, based on the control signal. At the time of a limp mode, the AND gates 8 and 12 are closed and FETs 2 and 3 are made open. At the time of runaway of CPU, the AND gate 9 is close and the FET 2 is made open, and the output of the OR gate 13 is made 'H', and the FET 3 is made short.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device for driving a DC brushless motor used for driving various joint mechanisms of a manipulator used in a space station, for example.

[0002]

2. Description of the Related Art Manipulators used in space stations and the like have a plurality of degrees of freedom, for example, six degrees of freedom, and each axis has a motor and a servo sensor. FIG. 2 is a diagram showing a configuration of a manipulator having 6 degrees of freedom. In this manipulator, a shoulder roll joint portion 22 and a shoulder pitch joint portion 23 are provided on a base portion 21 attached to a space station,
The arm 24 is supported by these. An elbow pitch joint section 25 is provided at the tip of the arm 24, and an arm 26 is provided via the elbow pitch joint section 25. Arm 2
A wrist pitch joint portion 27, a wrist yaw joint portion 28, and a wrist roll joint portion 29 are provided at the tip of 6, and an end effector 30 is further provided via these.
The end effector 30 holds and releases various payloads 31.

As described above, there are a total of six joint mechanism portions, and the total number of rotary shafts is six. Each joint mechanism section has a motor, a servo sensor, and the like.
Further, the electronic circuit section for controlling each joint mechanism section is independently arranged in the vicinity of each joint mechanism section in order to reduce the harness and to limit the length of the signal line and the like.

The manipulator having such a structure is used for various experiments at a space station. In this case, since there is a movable payload for various experiments on the space station platform, the payload 31 held by the end effector 30 may move independently of the operation of the manipulator. When repairing, an astronaut may directly move the arm in his hand.

In such a case, the motor of each joint mechanism is not driven. However, the angle of the joint mechanism is changed by an external force, and the motor rotates. Then, the motor acts as a generator and a current flows through the coil inside the motor, so that torque that prevents the displacement of each joint mechanism is generated. this is,
The load on the movement of the payload 31 may impede the stable movement of the payload 31, or the workability of the astronaut may be reduced.

In order to prevent such a problem, it is necessary to set the state where the current flowing through the motor is zero, that is, the so-called limp mode (current zero mode). Conventionally, when the motor is set to the limp mode, the current flowing through the motor is detected and the closed loop control is performed so that the current becomes zero. However, in this method, the control is complicated, and there are influences such as a current detection error and a control delay.

On the other hand, considering the case where the motor is stopped from the state in which the motor is being driven in order to shift each joint mechanism section, simply stopping the drive control does not immediately stop the rotation due to the influence of inertia. Especially in outer space, since the gravity is small, the inertia acts more and the time from the stop of the drive control to the stop of the rotation of the motor becomes longer. Therefore, a braking mechanism is needed.

A mechanical brake or an electromagnetic brake is generally used as the braking mechanism. However, the mechanical brake may damage the motor when sudden braking is applied in an emergency such as when the CPU used internally runs away, and shortens the life of the joint mechanism. Further, since the electromagnetic brake is realized by performing closed-loop control of the motor, when the control CPU or the like runs out of control, the control for braking cannot be performed and the motor cannot be stopped.

[0009]

As described above, the prior art is as follows.
Since the limp mode is set by performing the closed loop control so that the current flowing through the motor becomes zero, there are problems that the control is complicated and the optimum control is difficult.

Further, since a mechanical brake or an electromagnetic brake realized by closed loop control of the motor is used as a braking mechanism for stopping the rotation of the motor, the mechanical brake shortens the life of the joint mechanism and The electromagnetic brake had a problem that the braking function was stopped when control was impossible.

The present invention has been made in consideration of such circumstances, and the first object thereof is to provide a motor drive device capable of easily and surely realizing a zero current state. To do.

A second object is to provide a motor drive device which can surely stop the rotation of the motor when the motor rotation control becomes abnormal without using a mechanical mechanism.

[0013]

In order to achieve the first object, a first invention is to turn on / off application of a predetermined high level voltage to each of three coils of a DC brushless motor. ON / OFF of application of a predetermined low level voltage to each of the three high level side switching means such as FETs and each of the three coils
For controlling the low-level side switching means such as FETs, and the three high-level side switching means and the three low-level side switching means are turned on / off in a predetermined order in order to rotate the DC brushless motor.
A rotation control means for controlling and a predetermined mode time control means such as an AND gate are provided, and when a predetermined mode such as a limp mode is designated, the predetermined mode time control means causes the rotation control means to perform The control of the three high-level side switching means and the three low-level side switching means is stopped, and the three high-level side switching means and the three low-level side switching means are opened respectively.

In order to achieve the second invention, the second
Of the present invention turns on / off the application of a predetermined high level voltage to each of the three coils of the DC brushless motor.
Three high-level side switching means such as FETs for turning off, and three for turning on / off application of a predetermined low-level voltage to each of the three coils.
Rotation control for ON / OFF controlling the three high level side switching means and the three low level side switching means in a predetermined order in order to rotate the three low level side switching means such as FETs and the DC brushless motor. Means, an abnormality detection means such as a watchdog timer for detecting an abnormality of the rotation control means, and an abnormality time control means including, for example, an AND gate, an OR gate and an inverter, and the abnormality detection means controls the rotation control means. When an abnormality is detected, the abnormal time control means stops the control of the three high level side switch means and the three low level side switch means by the rotation control means, and the three high level side switch means. Are opened respectively, and the three low-level side switch means are Re was to be short-circuited.

[0015]

According to the first aspect of the invention, when a predetermined mode such as a limp mode is designated, the predetermined mode control means controls the rotation control means to control the three high-level side switch means and the three low-level control means. The control of the level-side switch means is stopped, and the three high-level side switch means and the three low-level side switch means are brought into the open state, respectively, so that no current flows in each coil of the DC brushless motor. It is formed.

According to the second aspect of the invention, when abnormality of the rotation control means is detected by the abnormality detection means, the abnormality control means causes the rotation control means to control the three high-level side switch means and the three control means. The control of the low-level side switching means is stopped, the three high-level side switching means are opened respectively, and the three low-level side switching means are respectively short-circuited, so that each of the DC brushless motors is The coils are short-circuited to each other, and a state in which a stop torque is generated is formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a main configuration of a manipulator configured by applying the motor drive device according to the present embodiment. The appearance of the manipulator of this embodiment is similar to that of the conventional one shown in FIG. 2, for example, but each joint mechanism section has an electric circuit as shown in FIG.

In the figure, M is a DC brushless motor as a power source for displacing each joint. This DC brushless motor M has three coils 1U, 1V and 1W of U phase, V phase and W phase, and has 120 deg.
A sine wave whose phase is shifted each time is applied, and the sine wave is driven by controlling its amplitude. Note that it is necessary to detect the position by an angle sensor attached to the motor shaft and perform control for matching the phases, but a configuration for that purpose is omitted.

Field effect transistors (FET) 2U, 2
V, 2W, 3U, 3V, 3W, diode 4 for regenerative power
U, 4V, 4W, 5U, 5V, 5W, comparator 6
U, 6V, 6W, sawtooth wave oscillator 7, AND gate 8
U, 8V, 8W, 9U, 9V, 9W, level conversion circuit 1
0U, 10V, 10W, inverters 11U, 11V, 1
1W, AND gates 12U, 12V, 12W, OR gates 13U, 13V, 13W, level conversion circuits 14U, 1
The 4V, 14W, the watchdog timer 15, the inverter 16, the current detection resistors 17U, 17W, the current detection circuit 18, and the A / D converter 19 form a drive circuit for the DC brushless motor M.

FETs 2U, 2V, 2W, 3U, 3V, 3
The Ws are connected as shown in the figure and constitute a so-called three-phase voltage source inverter. In addition, FET2U, 2V, 2W,
The application of the high-level side voltage (here, 28V) to each coil 1U, 1V, 1W is turned on / off.
The FETs 3U, 3V and 3W are connected to the coils 1U, 1V,
The application of the low-level voltage (here, 0 V) to 1 W is turned on / off.

Regenerative power diodes 4U, 4V, 4W,
5U, 5V, 5W are FETs 2U, 2V, 2W, 3U,
They are connected in parallel to 3V and 3W, respectively. Comparator 6U, sawtooth wave oscillator 7, AND gate 8
U, 9U, level conversion circuit 10U, inverter 11U,
The AND gate 12U, the OR gate 13U, and the level conversion circuit 14U form a circuit that controls the FETs 2U and 3U to control the energization of the U-phase coil 1U. That is, to the comparator 6U, a U-phase control signal generated by a CPU (not shown) and obtained by D / A conversion is input to the non-inverting input terminal, and the sawtooth wave oscillator 7 oscillates a sawtooth wave. The signal is input to the inverting input terminal. The output of the comparator 6U is the AND gates 8U and 9U.
Is input to the level conversion circuit 10U via the, and the level is converted by the level conversion circuit 10U and supplied to the gate of the FET 2U. The output of the comparator 6U is
After the logic is inverted by the inverter 11U, it is input to the level conversion circuit 14U through the AND gate 12U and the OR gate 13U, and the level is converted by the level conversion circuit 14U and supplied to the gate of the FET 3U.

Comparator 6V, sawtooth wave oscillator 7,
AND gates 8V, 9V, level conversion circuit 10V, inverter 11V, AND gate 12V, OR gate 13V
The level conversion circuit 14V has a configuration similar to that of the U-phase system described above, and constitutes a circuit that controls the FETs 2V and 3V to control the energization of the V-phase coil 1V.

A comparator 6W, a sawtooth oscillator 7,
AND gates 8W and 9W, level conversion circuit 10W, inverter 11W, AND gate 12W, OR gate 13W
The level conversion circuit 14W has a configuration similar to that of the U-phase system described above, and constitutes a circuit that controls the FETs 2W and 3W to control the energization of the W-phase coil 1W.

By the way, AND gates 8U, 8V, 8W,
12U, 12V, 12W has comparators 6U, 6
In addition to V and 6 W outputs, a limp signal output from a CPU (not shown) is input. Further, the AND gates 9U, 9V, 9W have AND gates 8U, 8V, 8W.
In addition to the output of, the signal obtained by logically inverting the output of the watchdog timer 15 by the inverter 16 is input. In addition to the outputs of the AND gates 12U, 12V, 12W, the outputs of the watchdog timer 15 are input to the OR gates 13U, 13V, 13W.

The watchdog timer 15 operates independently of the operation of the CPU (not shown) to monitor the operating state of the CPU (not shown), and outputs "L" when normal.
The output is set to the "H" level at the level and at the time of runaway.

The current detecting resistors 17U and 17W are respectively inserted between the U-phase coil 1U and the FETs 2U and 3U, or between the W-phase coil 1W and the FETs 2W and 3W, and between both ends thereof. Then, a voltage of a level corresponding to the magnitude of the current flowing through the U-phase coil 1U or the W-phase coil 1W is generated. The current detection circuit 18 includes the current detection resistor 1
The magnitude of the current flowing through the U-phase coil 1U or the W-phase coil 1W is detected by detecting the voltage generated between both ends of 7U and 17W, and this is notified to the CPU (not shown). To output signals IU and IW. A /
The D converter 19 digitizes the signals IU and IW output from the current detection circuit 18 and CPU (not shown).
Give to.

Next, the operation of the manipulator configured as above will be described. Since the operation of the manipulator itself is the same as the conventional one, the description thereof will be omitted, and the electrical operation of one joint will be described here.

First, from the CPU (not shown), a U-phase and a V-phase which are sine waves each having a phase difference of 120 deg.
The respective control signals of the phase and the W phase are given. CP
U (not shown) generates these control signals,
The rotation speed of the DC brushless motor M is detected based on the detection result of a position detector (not shown) provided in the DC brushless motor M, and speed calculation is performed with the speed command value. Further, the CPU (not shown) is a current detection circuit 1
The current control calculation is performed by using the current values flowing in the V-phase coil 1V and the W-phase coil 1W, which are detected by 8 and are notified via the A / D converter 19. Then, the control signal is generated based on the results of the two control calculations.

Upon receipt of the U-phase control signal, the comparator 6U subjects this control signal to pulse width modulation using the sawtooth wave oscillated by the sawtooth oscillator 7 as a carrier. By the way, in a normal operation mode in which each joint is arbitrarily displaced to move the payload, the CPU (not shown) sets the limp signal to the "H" level. If the CPU (not shown) is normal, the watchdog timer 15 sets the output to the "L" level. Thus, in this state, AND gate 8U and AND gate 9U are in a state of directly supplying the output of comparator 6U to level conversion circuit 10U. The AND gate 12U and the OR gate 13U are in a state of giving the output of the inverter 11U to the level conversion circuit 14U as they are.

Thus, in the normal operation mode, the FET 2U is turned ON / O based on the output of the comparator 6U (a signal obtained by pulse width modulation of the U-phase control signal).
The FET 3U is turned on / off based on the signal obtained by FF and inverting the logic of the output of the comparator 6U.

Such an operation is performed on the basis of the V-phase control signal even in the comparator 6V, the AND gates 8V, 9V and 12V, the inverter 11V, the OR gate 13V, the level conversion circuits 10V and 14V and the FETs 2V and 3V. 6W, AND gate 8W, 9W,
12W, inverter 11W, OR gate 13W, level conversion circuits 10W and 14W, and FETs 2W and 3W also W
It is performed based on the phase control signal. Thus, the three-phase coils 1U, 1V, 1W in the DC brushless motor M
Are to be energized based on the U-phase control signal, the V-phase control signal, and the W-phase control signal.
The brushless motor M will rotate.

When the limp mode is set, the limp signal from the CPU (not shown) is set to the "L" level. Then, AND gates 8U, 8V, 8
W, 12U, 12V, 12W are all comparators 6U, 6V, 6W or inverters 11U, 11V, 1
The passage of the output of 1 W is blocked, and the output is fixed to the "L" level. As a result, the FETs 2U, 2V, 2W, 3U,
All 3V and 3W are fixed in the open state.

In this state, even if the DC brushless motor M is rotated by an external force, the FET
Since 2U, 2V, 2W, 3U, 3V, 3W are all in the open state, no current flows through the coils 1U, 1V, 1W, and no torque that blocks rotation is generated. When the electromotive force in the DC brushless motor M exceeds the power supply voltage, a current flows through the regenerative power diodes 4U, 4V, 4W, but the electromotive force in the DC brushless motor M is generally a dozen V and the power supply voltage is high. Is never exceeded.

On the other hand, when the CPU (not shown) runs out of control, the watchdog timer 15 outputs "H" level when detecting this. Then, AND gate 9
U, 9V, 9W and OR gate 13U, 13V, 13
W blocks the output of the comparators 6U, 6V, 6W or the inverters 11U, 11V, 11W, and the AND gates 9U, 9V, 9W have the output at the "L" level, and the OR gates 13U, 13V, 13W The output is fixed at "H" level. As a result, FE
T2U, 2V, 2W are open, and FET3
U, 3V and 3W are fixed in a short state.

In this state, the coils 1U, 1V, 1W of the DC brushless motor M are short-circuited with each other, and a stop torque is generated. Due to this stop torque, the DC brushless motor M stops rotating.

As described above, according to this embodiment, the comparators 6U, 6V, 6W and the level conversion circuits 10U, 10
Between V and 10W and inverters 11U, 11V, 1
AND gates 8U, 8V, 8W and AND gates 12U, 12V, 12W are respectively inserted between 1W and the level conversion circuits 14U, 14V, 14W, and these AND gates 8U, 8V, 8W are provided in the limp mode.
FETs 2U, 2V, 2W, 3U, 3V, 3W are turned on / off by a normal control signal by W, 12U, 12V, 12W.
OFF control is stopped and each FET2U, 2V, 2W, 3
Since U, 3V and 3W are all fixed in the open state, the current zero state of the DC brushless motor M can be realized easily and reliably with a very simple structure.

Further, according to this embodiment, the comparator 6
U, 6V, 6W and level conversion circuits 10U, 10V, 10
AND gates 9U, 9V, 9W and OR gates 13U, 13 between W and between inverters 11U, 11V, 11W and level conversion circuits 14U, 14V, 14W.
V and 13W are respectively inserted, and when the watchdog timer 15 detects a runaway of the CPU (not shown), the AND gates 9U, 9V and 9W and the OR gates 13U, 13V and 13W are used to control the FET 2U by a normal control signal. , 2V, 2W, 3U, 3V, 3W ON /
Since the OFF control is stopped, the FETs 2U, 2V, 2W are fixed in the open state, and the FETs 3U, 3V, 3W are fixed in the short state, the DC brushless motor M can be brought into a state in which a stop torque is generated without energization control. It is possible to surely stop the rotation of the DC brushless motor M without using a mechanical brake and even when the CPU (not shown) runs out of control.

As a result, in the limp mode, a very useful manipulator which does not impede the smooth movement of the payload or requires an astronaut to operate an arm more than necessary is realized. .

Further, even if the CPU runs out of control, the manipulator does not operate abnormally, and a highly reliable manipulator capable of surely stopping the operation is realized.

The present invention is not limited to the above embodiment. For example, in the above embodiment, an example in which the motor drive device of the present invention is applied to a manipulator is shown, but the motor drive device of the present invention drives a DC brushless motor provided in the joint mechanism portion of the manipulator. However, the present invention is not limited thereto, and can be applied to driving a DC brushless motor provided in another device.

In the above embodiment, the means for putting the DC brushless motor into the zero current state and the means for generating the stop torque in the DC brushless motor are both shown. It may be provided with only one. In addition, various modifications can be made without departing from the scope of the present invention.

[0042]

According to the first aspect of the present invention, there are three FEs for turning on / off application of a predetermined high level voltage to each of the three coils of the DC brushless motor.
ON / OFF of high level switch means such as T and application of predetermined low level voltage to each of the three coils
Three low-level side switching means such as FETs for turning off and the three high-level side switching means and the three low-level side switching means are turned on / off in a predetermined order in order to rotate the DC brushless motor. O
A rotation control means for FF control and a predetermined mode time control means such as an AND gate are provided, and when a predetermined mode such as a limp mode is designated, the predetermined mode time control means is operated by the rotation control means. Since the control of the three high-level side switching means and the three low-level side switching means is stopped and the three high-level side switching means and the three low-level side switching means are opened respectively, The motor drive device can easily and surely realize the zero current state.

In order to achieve the second invention, a second
Of the present invention turns on / off the application of a predetermined high level voltage to each of the three coils of the DC brushless motor.
Three high-level side switching means such as FETs for turning off, and three for turning on / off application of a predetermined low-level voltage to each of the three coils.
Rotation control for ON / OFF controlling the three high level side switching means and the three low level side switching means in a predetermined order in order to rotate the three low level side switching means such as FETs and the DC brushless motor. Means, an abnormality detection means such as a watchdog timer for detecting an abnormality of the rotation control means, and an abnormality time control means including, for example, an AND gate, an OR gate and an inverter, and the abnormality detection means controls the rotation control means. When an abnormality is detected, the abnormal time control means stops the control of the three high level side switch means and the three low level side switch means by the rotation control means, and the three high level side switch means. Are opened respectively, and the three low-level side switch means are Re since such a short state, without using a mechanical mechanism, a motor rotation control is a motor drive device capable of reliably stopped the rotation of the motor if it becomes abnormal.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part configuration of a manipulator configured by applying a motor drive device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a manipulator having 6 degrees of freedom.

[Explanation of symbols]

M ... DC brushless motor 1U, 1V, 1W ... Coil 2U, 2V, 2W, 3U, 3V, 3W ... Field effect transistor (FET) 4U, 4V, 4W, 5U, 5V, 5W ... Regenerative power diode 6U, 6V, 6W ... Comparator 7 ... Sawtooth oscillator 8U, 8V, 8W, 9U, 9V, 9W, 12U, 12
V, 12W ... AND gate 10U, 10V, 10W, 14U, 14V, 14W ... Level conversion circuit 11U, 11V, 11W ... Inverter 13U, 13V, 13W ... OR gate 15 ... Watchdog timer 16 ... Inverter 17U, 17W ... For current detection Resistor 18 ... Current detection circuit 19 ... A / D converter

Claims (4)

[Claims] 1. A motor drive device for driving a DC brushless motor, wherein ON / OFF of application of a predetermined high level voltage is applied to each of three coils of the DC brushless motor.
Three high-level side switching means for turning on and off the application of a predetermined low-level voltage to each of the three coils, and to rotate the DC brushless motor. Rotation control means for ON / OFF controlling the three high-level side switching means and the three low-level side switching means in a predetermined order; and the rotation control means for controlling the three states when a predetermined mode is designated. High-side switch means and said 3
Stop the control of the two low-level side switch means, and
A motor drive device, comprising: one high-level side switch means and a predetermined mode control means for opening each of the three low-level side switch means. 2. A motor drive device for driving a DC brushless motor, wherein application of a predetermined high level voltage to each of the three coils of the DC brushless motor is turned on / off.
Three high-level side switching means for turning on and off the application of a predetermined low-level voltage to each of the three coils, and to rotate the DC brushless motor. , Rotation control means for ON / OFF controlling the three high-level side switch means and the three low-level side switch means in a predetermined order, an abnormality detection means for detecting abnormality of the rotation control means, and this abnormality detection When the abnormality of the rotation control means is detected by the means, the control of the three high level side switch means and the three low level side switch means by the rotation control means is stopped, and the three high level side switches are stopped. Each of the means is in an open state, and the three low-level side switch means are in a short state. A motor drive device comprising: 3. A motor drive device for driving a DC brushless motor, wherein ON / OFF of application of a predetermined high level voltage is applied to each of the three coils of the DC brushless motor.
Three high-level side switching means for turning on and off the application of a predetermined low-level voltage to each of the three coils, and to rotate the DC brushless motor. Rotation control means for ON / OFF controlling the three high-level side switching means and the three low-level side switching means in a predetermined order; and the rotation control means for controlling the three states when a predetermined mode is designated. High-side switch means and said 3
Stop the control of the two low-level side switch means, and
One high-level side switch means and the three low-level side switch means are respectively in open states, a predetermined mode control means, an abnormality detection means for detecting an abnormality of the rotation control means, and the rotation control by the abnormality detection means. When the abnormality of the means is detected, the control of the three high-level side switch means and the three low-level side switch means by the rotation control means is stopped, and the three high-level side switch means are opened respectively. In addition, the motor drive device is provided with abnormal time control means for making each of the three low-level side switch means short-circuited. 4. The motor drive device according to claim 1, wherein the DC brushless motor to be driven is provided in the joint mechanism portion of the manipulator.